Body configuration and joint moment analysis during standing long jump in 6-yr-old children and adult males.

The purpose of the present study was to compare the body configurations and the joint function during standing long jump in 6-yr-old children and adult males. Twelve healthy adult males and eight (one male and seven females) 6-yr-old kindergartners participated in this study. Subjects performed standing long jump on a force platform with full effort. Body segment and joint angles were analyzed by high speed videography (100 frames.s-1). Using kinetic and kinematic data, joint moments, power, and work done were calculated through a free body diagram. Average standing long jump performances were +1.5 SD above Japanese norm in both adults and children. A wide range of motion of the lower limb segments during flight phase was found in the adults. In the crouch prior to take off, joint muscle power peaks appeared in the same order, and joint contribution to the total work done showed almost the same values in both adults and children. It is suggested that gross motor pattern before take off is almost accomplished by the 6-yr-old. Judging by hip joint work, adult performance was much better than that of children, since the adults exerted relatively higher negative work from the onset of preparatory movement to the point of lowest center of gravity during crouch. It was concluded that skilled 6-yr-old children have not fully developed either hip negative work during preparatory movement or body configuration in the flight phase, although gross motor pattern before take off phase was accomplished to skilled adult level.